Dell A920 ink carts

My daughter recently purchased a second-hand Dell P4 that came with the
above referenced printer. I normally order my ink from PrintPal for my Canon
printer but am unable to find the Dell replacements listed. In reading
through this ng I see that the A920 is apparently a modified Lexmark unit
and am wondering if anyone has found it possible to substitute Lexmark
replacement carts to use in the A920.

Barring that, does anyone have any recommendations for purchase of the Dell
carts for the thing at reasonable prices from reputable on-line ink vendors?
A Google search turned up a zillion ink sellers but I'm not familiar with
any but PrintPal.

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dvus